Magnetic erasing device

ABSTRACT

A magnetic erasing device including a magnet that includes an S pole and an N pole extending along an axial direction of the magnet, and a rotation mechanism for rotating the magnet in a housing around an axis of the magnet, wherein lines of magnetic force generated around the axis of the magnet during rotation of the magnet are designed to be applied to magnetic particles in the microcapsules to erase a visible image on a magnetic panel when the axis of the magnet is spaced from a surface of the magnetic panel by a predetermined distance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/679,767, filed on Aug. 17, 2017, which claims priority to JapaneseApplication No. 2016-161634, filed on Aug. 22, 2016, which applicationis hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a magnetic erasing device.

BACKGROUND

A magnetophoretic type magnetic panel has been come into practical use.Such a magnetic panel includes magnetic particles and a dispersionliquid in each microcapsule. The magnetic particles in the microcapsulesare migrated to draw desired letters, symbols, pictures, etc. by amagnetic field applied from a magnetic pen having a magnet at the tipthereof. A magnetically reversal type magnetic panel in which eachmagnetic display body has an N pole and an S pole at front and backsides and which each pole is colored with different colors has also beenput to practical use.

Characters, symbols and the like drawn on the magnetic panel can beerased by using an erasing tool with magnetization (hereinafter may bereferred to as a magnetic erasing device) to the front side or the backside of the magnetic panel. For example, a recording apparatus inJapanese patent publication No. 2000-276082 includes a magnetic sheethaving microcapsules for recording and an erasing sheet provided on theback side of the magnetic sheet, and characters and figures on themagnetic sheet are erased by reciprocating while maintaining the erasingsheet substantially parallel to the magnetic sheet by utilizing themotive power of the motor. International patent publication No. WO01/048548 discloses a magnetic directing device for amagnetic-body-reversal-display-panel which enables to erase letters,graphics, etc. by applying a magnetic force in an adverse directionopposite to the magnetic force applied during recording, from thewriting surface. Japanese patent registration No 4089808 discloses amagnetophoretic display sheet including two or more types of magneticparticles in each microcapsule, which is erasable from an upper side.

As shown in WO 01/048548, an erasing device used in a conventionalmagnetic panel utilizes lines of magnetic force generated from magnetsfixed in a housing, as the results, characters, figures, etc. in areasthat the lines of magnetic force in a certain direction are applied aredeleted, but not deleted in other areas. Therefore, in order to evenlyerase letters, figures, etc. drawn on the magnetic panel, the user needsto move the erasing device in all directions on the magnetic panel toapply magnetic field from various angles, which is troublesome inoperation, this is the problem. Also, in the type of driving the erasingsheet on the back side of the magnetic sheet as in No. 2000-276082, itis not possible to erase characters from the front side of the magneticpanel (the surface written by the magnetic pen), which is notconvenient, it is the problem.

SUMMARY

Embodiments of the present invention relate to a magnetic erasing devicefor erasing letters, figures, symbols, etc. drawn on a magnetic panelincluding magnetized display bodies, and particular embodiments relateto a magnetic erasing device with an improved erasing efficiency bychanging the direction of a magnetic field applied to the magneticpanel.

Embodiments of the present invention solve conventional problems, andprovide a magnetic erasing device for easily erasing characters etc.drawn on a magnetic panel.

In the present invention, a magnetic erasing device for a magnetic panelcomprises a housing, an internal space being formed in the housing. Amagnetic field generator is accommodated in the housing and generates amagnetic field. A magnetic field changer changes the magnetic fieldgenerated by the magnetic field generator.

In some embodiments, the magnetic field generator includes at least onepermanent magnet and the magnetic field changer includes a rotatingmechanism for rotating the permanent magnet.

In some embodiments, the magnetic field generator includes a rotatingmember provided in the housing and at least first and second magnetsattached to the rotating member, an S pole of the first magnet arrangedat a front side and an N pole of the second magnet arranged at a frontside, and the magnetic field changer changes the magnetic field byrotating the rotating member.

In some embodiments, the magnetic field generator includes a rotatingmember provided in the housing and at least first and second magnetsattached to opposite positions of the rotating member, an S pole and anN pole formed on the surface of the first magnet, and an S pole and Npole formed on the surface of the second magnet, and the lines ofmagnetic force from the N pole to the S pole between the first and thesecond magnets are formed.

In some embodiments, the first and second magnets are disposed in arotationally symmetrical.

In some embodiments, the magnetic field generator includes at leastfirst and second magnets so that an S pole and an N pole are formedalong the axial direction respectively and the magnetic field changerrotates the first and second magnets about their axes.

In some embodiments, the magnetic field changer rotates the first andthe second magnets so that the S pole and the N pole are synchronizedwith each other.

In some embodiments, the magnetic field changer includes a rotatingmechanism for rotating the first and second magnets by first and secondgears, a gap between the first and second magnets adjusted by the firstand second gears.

In some embodiments, the magnetic field generator includes an annularmagnetic member having a plurality of protrusions formed at the innerperiphery, a plurality of coils wound around the plurality ofprotrusions, and current applying means for applying a current to theplurality of coils, and the magnetic field changer controls a timing ofapplication of current by the current applying means.

In some embodiments, the plurality of protrusions are arranged at equalintervals and the magnetic field changer controls the timing ofapplication of current such that a pair of opposing protrusionssuccessively generate an S pole and an N pole.

In some embodiments, the magnetic field generator includes a columnariron core and a coil wound around the iron core, and the magnetic fieldchanger applies an AC waveform current to the coil.

In some embodiments, the magnetic field generator is disposed at aposition recessed from an end of the housing by a predetermineddistance.

In some embodiments, the magnetic erasing device further comprises aninput switch for activating the magnetic field changer.

In some embodiments, the magnetic erasing device further comprised asensor for operating the magnetic field changer.

In some embodiments, the magnetic erasing device further comprises avariable mechanism for varying the distance of the magnetic fieldgenerator from the end of housing.

In some embodiments, the magnetic erasing device further comprises inputmeans for receiving a instruction from a user, the magnetic fieldgenerator adjusts the variable mechanism in response to the input fromthe user.

In some embodiments, the magnetic erasing device further comprises acover member covering an open end of the housing, the surface of thecover member is provided with a material for facilitating sliding.

In some embodiments, the magnetic field changer includes a motor and abattery as a power source.

In some embodiments, the housing is made of a magnetic material.

According to embodiments of the present invention, since the magneticfield generated in the housing is changed, it is possible to obtain thesame effect as the action of lines of magnetic force in variousdirections on the magnetic panel, thereby characters etc. drawn on themagnetic panel being erased more efficiently. This improves the user'sconvenience.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 , which includes FIGS. 1A and 1B, shows a magnetic erasing deviceaccording to a first embodiment of the present invention. FIG. 1A is atop view of the magnetic erasing device and FIG. 1B is a sectional viewof A-A line of the magnetic erasing device.

FIG. 2 is a plane view of a support attached to a magnet.

FIG. 3A and FIG. 3B show a block diagram showing an electricalconfiguration example of the magnetic erasing device of the presentembodiment.

FIG. 3C and FIG. 3D show a block diagram showing another electricalconfiguration example of the magnetic erasing device of the presentembodiment.

FIG. 4A is a sectional view showing an exemplified configuration of amagnetic panel, and FIG. 4B shows an example of erasure by a magneticerasing device.

FIG. 5A is a sectional view for schematically illustrating thegeneration of a magnetic field in the magnetic erasing device of thefirst embodiment, FIG. 5B is a plane view for schematically illustratinggeneration of a magnetic field as viewed from the bottom of the housing,and FIG. 5C is a view for explaining an erasing range.

FIGS. 5D-5E show a modification of the first embodiment of the presentinvention.

FIGS. 5F-5I show a modification of the first embodiment of the presentinvention.

FIG. 6 , which includes FIGS. 6A-6D, shows a modified example of themagnetic erasing device according to the first embodiment of the presentinvention.

FIG. 7A is a plane view of an inside of the housing taken the upper sideof the magnetic erasing device according to the second embodiment, FIG.7B is a sectional view of B-B line of FIG. 7A.

FIGS. 8A and 8B show an example of a rod-shaped permanent magnetapplicable to the second embodiment.

FIGS. 8C-8E explain a modification of the second embodiment.

FIG. 8F shows an example when the magnetic erasing device is configuredas a pen type according to the present embodiment

FIG. 9 shows a plane view for a main part of a magnetic erasing deviceaccording to a third embodiment of the present invention.

FIG. 10 , which includes FIGS. 10A and 10B, is a timing chart ofcurrents applied to the third embodiment.

FIG. 11 shows changes in lines of magnetic force in the stator duringtime periods T1 to T9.

FIG. 12 , which includes FIGS. 12A-12C, shows an example of a voltage(current) waveform applied to a coil.

FIG. 13 , which includes FIGS. 13A and 13B, shows a modified example ofthe magnetic erasing device according to the third embodiment of thepresent invention.

FIG. 14 which includes FIGS. 14A-14D, explains a main part of a magneticerasing device according to a fourth embodiment of the presentinvention.

The following reference numerals can be used in conjunction with thedrawings:

-   -   10, 10 A, 10 B: magnetic erasing device    -   20: housing    -   22: internal space    -   24: open end    -   30: support    -   40: battery    -   50: motor    -   60, 62: gear    -   70: rotor    -   80: magnet    -   100: magnetic panel    -   110: top sheet    -   120: back sheet    -   130: microcapsule    -   200: support    -   210, 220: permanent magnet    -   230, 232, 234: gear    -   300, 302: stator    -   310: protrusion    -   320: coil    -   400, 410, 420: iron core    -   430: coil

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Next, embodiments of the present invention will be described in detailwith reference to the drawings. In a preferred embodiment of the presentinvention, a magnetic erasing device has a mechanism for dynamicallychanging a magnetic field for enabling to erase characters, figures,symbols etc. drawn by a magnetic pen on a magnetic panel by applying thechanging magnetic field to the magnetic panel. Please note that the sizeof each part shown in the drawing is not necessarily the same as thesize of the actual product.

FIG. 1 shows a magnetic erasing device according to a first embodimentof the present invention, FIG. 1A is a top view of the magnetic erasingdevice, FIG. 1B is a cross-sectional view of A-A line of the magneticerasing device. The magnetic erasing device 10 of the present embodimentincludes a cylindrical housing 20 in which a space 22 is formed. Thehousing 20 may be made of various materials such as metal and resin, butis preferably made of a magnetic material such as iron. In the internalspace 22 of the housing 20, a disk-shaped support 30 is attached. Thematerial of the support 30 is arbitrary, but it is composed of, forexample, a metal. For example, the side surface of the support 30 isfixed to the inner wall of the housing 20 with a resin or the like, andthe internal space 22 is divided into upper and lower spaces by thesupport 30.

A battery 40, a motor 50, and a gear 60 are accommodated in the upperinternal space. The battery 40 is disposed at one end of the support 30,and the motor 50 is disposed at the other end. The battery 40 is a powersource for driving the motor 50. The battery 40 and the motor 50 areelectrically connected to circuit components/wirings (not shown) mountedon the support 30. Further, a shaft 32 is rotatably attached tosubstantially the center of the support 30. A spur gear 60 is attachedto one end of the shaft 32, and a rotating member 70 is attached to theother end of the shaft 32. A worm gear 62 is connected to the driveshaft 52 of the motor 50, and the worm gear 62 meshes with the spur gear60. Therefore, when the drive shaft 52 of the motor 50 rotates, itsrotation is transmitted to the shaft 32 via the worm gear 62 and thespur gear 60 for rotating the rotating member 70.

In the lower internal space, the circular rotating member 70 and aplurality of magnets 80, 82 are accommodated. The rotating member 70 ismade of an arbitrary material, but is preferably made of a magneticmaterial such as iron. The rotating member 70 is connected to the shaft32 as described above and is rotatable by the motor 50. The first andsecond magnets 80, 82 are mounted on one surface of the rotating member70. FIG. 2 shows a plane view of a rotating member 70 to which themagnets 80, 82 are attached. The first and second magnets 80, 82 may bethe same shape. The first and second magnets 80, 82 are attached to therotating member 70 so that their poles are opposite to each other. Inthe example of drawing, each magnet 80, 82 has the same rectangularshape, and each magnet is disposed at a position at a radius r 1, r 2from the axial center C of the rotating member 70. Preferably, r 1=r 2,and the first and second magnets 80, 82 are arranged rotationallysymmetrically. Further, the N pole of the first magnet 80 faces therotating member 70 to expose the S pole, and conversely the S pole ofthe second magnet 82 faces the rotating member 70 to expose the N pole.

The rotating member 70 or the first and second magnets 80, 82 areadjusted to be recessed from an open end 24 of the housing 20 by adistance d, as shown in FIG. 1B. A cover 26 for shielding the internalspace 22 is attached to the open end 24 of the housing 20. The cover 26is made of a nonmagnetic material, for example resin or plastic, fortransmitting the magnetic field generated by the magnets 80, 82.

FIG. 3A and FIG. 3B are a diagram showing an exemplified electricalconfiguration of the magnetic erasing device of the present embodiment.FIG. 3A shows the simple configuration. The magnetic erasing device 10includes, for example, a switch 90 on the top surface of the housing 20.The user operates on/off of the switch 90 to drive or stop the motor 50.

FIG. 3B includes a controller 92 for controlling the driving of themotor 50 and an user interface I/F 94 for receiving inputs from theuser. The controller 92 activates the motor 50 or adjusts the rotationalspeed of the motor 50 according to the instruction from the user. Inaddition, the controller 92 may perform a timer function ofautomatically turning off the driving of the motor 50 after a certainperiod of time from the start up of the motor 50.

FIG. 3C and FIG. 3D is a block diagram showing another electricalconfiguration. This configuration includes a sensor 96. The sensor 96may be mounted on either surface of the housing 20, for example. Thesensor 96 may be a contact sensor for detecting any object (includinguser contact) that has been touched on the housing 20. The controller 92activates the motor 50 in response to the detection of contact by thecontact sensor 96 and stops the motor 50 when the contact is no longerdetected. In another preferable example, the sensor 96 may be a sensorthat included a light emitting element and a light receiving elementsuch as an optical mouse. In this case, the sensor detects, for example,that the magnetic erasing device has moved over the magnetic panel andthe controller 92 controls on/off of the motor 50 in response to thisdetection.

As shown in FIG. 1 , the magnets 80, 82 are located at the distance dfrom the open end 24 of the housing 20. The magnetic erasing device 10can have a variable mechanism for varying the distance d. The variablemechanism can be configured using known techniques. For example, thevariable mechanism includes a screw mechanism, which changes thevertical height of the rotating member 70 or the magnets 80, 82 byrotating the screws. In this case, an operation member for rotating thescrew may be provided so that the user can operate it from the outsideof the holder 20. Alternatively, the variable mechanism may include asliding mechanism to adjust the height of the rotating member 70 or themagnets 80, 82 by sliding the sliding member in the vertical direction.

Further, the variable mechanism may be electrically operated by anactuator. FIG. 3D shows a block diagram for operating the variablemechanism electrically. As shown in this figure, the actuator unit 98includes another motor, a driving member, or the like for driving thevariable mechanism. The controller 92 operates the variable mechanism bythe actuator unit 98 to adjust the distance d of the magnets 80, 82, inaccordance with an instruction from the user.

FIG. 4A shows an example of a magnetic panel that the magnetic pen ofthis embodiment can be used. The magnetic panel 100 includes a top sheet110, which is a transparent sheet capable of transmitting a magneticfield, for providing the display surface of the magnetic panel, a backsheet 120 opposite the top sheet 110, and a plurality of microcapsules130 two-dimensionally arranged in the space between the top sheet 110and the back sheet 120. The plurality of microcapsules 130 areaccommodated in a case (not shown).

Preferably, the microcapsule 130, for example, includes at least onekind of magnetic particles having a particle size of 0.1 μm to 1.0 μm,at least one kind of magnetic particles having a particle size of 1 μmto 20 μm, white nonmagnetic particles such as white titanium oxide,dispersion and additives in a transparent spherical cell. The size ofthe microcapsules is, for example, 50 to 650 μm. Such a magnetophoretictype magnetic panel is disclosed in, for example, Japanese patent No.4089808, which is incorporated by reference herein, and has thefollowing features.

Small particles are easily reacted in the direction of lines of magneticforce with horizontal lines of magnetic force.

In the magnetic pen having the vertical lines of magnetic force, thelarge and small magnetic particles are reacted to allow the front sideto change black for drawing characters.

When erasing from the front side of the magnetic panel, if only thehorizontal magnetic field lines are applied to the small particlessensitive to the horizontal lines of magnetic force, the small particlesmigrate in the direction of the lines of magnetic force to change white.At this time, since the large particles rarely react, they remain“black”, and the black can be seen through from the front side, so thatit does not completely become white, which generates decrease incontrast.

In order to erase characters, it is sufficient to react horizontal linesof magnetic force. On the contrary, a magnetic pen having horizontallines of magnetic force erase the written characters by itselfimmediately, which causing defects.

One microcapsule 130 forms one pixel. For example, as shown in FIG. 4B,when the magnetic field is applied to the microcapsule 130 by themagnetic pen 10 on the top sheet 110, as described above, in response tothe lines of magnetic force in the vertical direction from the magneticpen, the black magnetic particles in the microcapsules 130 migrate tothe front surface. In this manner, when the magnetic pen 10 is moved onthe top sheet 110, the magnetic particles in the microcapsules 130migrate in accordance with the movement to form images. On the otherhand, when erasing the images, an erasing magnet (not shown) is slid onthe top sheet 110, and small particles migrate to the front side inresponse to the lines of magnetic force in the horizontal direction fromthe erasing magnet to erase the images. In this case, it is desirablethat a certain clearance is provided between the erasing magnet and thetop sheet 110 so as to apply a large amount of horizontal lines ofmagnetic force to the magnetic panel.

Note that the microcapsule 130 is not necessarily limited to the abovestructure. For example, the microcapsule 130 may include permanentmagnet particles in a transparent spherical cells and the permanentmagnet particle may be magnetized so as to have N pole and S pole. Themagnetic panel may be erased from the front side or back side. Forexample, the permanent magnet particles of N pole may be painted black,and the permanent magnet particles of S pole may be painted white, andthe permanent magnet particles can move freely within the cell accordingto the magnetic field from the magnetic pen or erasing magnet.

In addition to the magnetophoresis type, the magnetic panel may be amagnetic reversal type magnetic sheet. Further, the magnetic panel 100may erase the drawn images by applying the magnetic field from the topsheet 110 or may erase the drawn images by applying the magnetic fieldfrom the back sheet 120.

Next, the operation of the magnetic erasing device of this embodimentwill be described. FIGS. 5A and 5B are diagrams schematically showinglines of magnetic force of the magnetic erasing device 10. When therotating member 70 or the first and second magnets 80, 82 arestationary, the lines of magnetic force M are generated from the N poletoward the S pole in the internal space 22 of the housing 20. Here, whenthe rotating member 70 is rotated, the direction of the lines ofmagnetic force M changes since the first and second magnets 80, 82 arerotated. At this time, the erasable area 150 is substantially equal tothe range (r 1+r 2) in which the first and second magnets 80, 82 rotate.

FIG. 4B is a schematic view for showing the erasure by the magneticerasing device on the top sheet 110 of the magnetic panel 100. When themagnetic erasing device 10 is moved in the Y direction on the surfaceside for recording, characters and the like are erased within the area.Since the first and second magnets 80, 82 are located at a distance dfrom the open end 24 of the housing 20, the horizontal component of thelines of magnetic force M directed from the N pole to the S pole isfacilitated to act on the magnetic panel 100. If d=0, since the verticaldirection of the lines of magnetic force M act on the magnetic panel100, it is difficult for the erasure to be clear due to the influence ofthe vertical component. Further, the component in the horizontaldirection of the lines of magnetic force M can be increased byestablishing the interval (r 1+r 2) between the first magnet 80 and thesecond magnet 82 to an appropriate value.

Next, a modified example of the first embodiment will be described. InFIGS. 5D and 5E, the rotating member 70A of the modified example has arectangular shape, and its central portion is rotatably attached to thesupport 30 through the shaft 32. An extending portion 72 extending inthe vertical direction is formed at one end portion of the rotatingmember 70A and an extending portion 74 is also formed on the other endportion similarly. Preferably, the rotating member 70A is made of amagnetic material, and the housing 20 is also made of a magneticmaterial. The magnet 80 is attached to one end portion of the rotatingmember 70A and the magnet 82 is attached to the other end portion of it.In a preferred embodiment, the extending portions 72, 74 are located ata height Q higher than the surface of the magnets 80, 82 to prevent theleakage of lines of magnetic force from the magnets 80, 82 to theoutside of the rotating member 70A. In a further preferred example, agap P is formed between the magnets 80, 82 and the extending portions72, 74 respectively to shield the lines of magnetic force of the magnets80, 82 by the extending portions 72, 74. In the present embodiment, Pmay be zero, that is, the magnets 80, 82 may be brought into closecontact with the extending portions 72, 74, or Q may be set to zero sothat the heights of the extending portions 72, 74 and the magnets 80, 82may be equal to each other.

Further, the opening of the housing 20 is covered with a cover 26. Asliding facilitation member 27 with a soft material and a low friction(for example, a non-magnetic material such as felt) is provided on thesurface of the cover 26. When sliding the magnetic erasing device 10 onthe top sheet 110 of the magnetic panel 100 as shown in FIG. 4B, thesliding of the magnetic erasing device is facilitated by the slidingfacilitation member 27 and scratches on the top sheet 110 are prevented.In addition to magnetic drawing, when drawing with a whiteboard markeror the like is performed on the top sheet 110, the drawing by thewhiteboard marker can be erased by the sliding facilitation member 27.

FIG. 5E shows an appearance of lines of magnetic force M of the magnets80, 82. The lines of magnetic force M is generated from the N pole tothe S pole as shown. Since the gap P between the magnet 80 and theextending portion 72 and the gap P between the magnet 82 and theextending portion 74 exist, the lines of magnetic force from the N poleare effectively absorbed by the extending portions 72 and 74 so that thelines of magnetic force can be accurately confined within the radiusrange of the rotating member 70A.

FIGS. 5F and 5G are further modified examples of the first embodiment.In this modified example, the orientations of the magnetic poles of themagnets 80A and 82A are different from those of the magnets 80 and 82.The magnet 80A is attached to one end portion of the rotating member 70Aand the magnet 82A is attached to the other end portion of it. The Spoles and the N poles of the magnets 80A and 82A are arranged in theradius direction of the rotating member 70A, the S pole of the magnet80A is opposed to the N pole of the magnet 82A. Alternatively, the Npole of the magnet 80A may be arranged to face the S pole of the magnet82A. For example, the N pole of the magnet 80A is attached to the sidesurface of the extending portion 72 and the S pole of the magnet 82A isattached to the side surface of the extending portion 74. The magnets80A, 82A are separated from the upper surface of the rotating member 70Aby a clearance Q. The height of the extending portions 72, 74 is higherthan the magnets 80A, 82A, similarly the above modified example. FIG. 5Ishows the appearance of the lines of magnetic force at this time. Withsuch the configuration, since the lines of magnetic force generated fromthe magnets 80A, 82A are shielded by the extending portions 72, 74, theerasing range by the magnetic erasing device is accurately defined tothe radius r1 of the magnet 80A and the radius r2 of the magnet 80B. Inthis example, Q may be zero so that the magnets 80A, 82A are broughtinto close contact with the upper surface of the rotating member 70A, orthe heights of the extending portions 72, 74 and the magnets 80A, 82Amay be equal.

FIG. 5H is a further modified example. In this example, the housing 20Aand the cover 26 are made of a non-magnetic material such as a plastic.In this case, the magnetic member 20B may be provided on the innerperiphery of the housing 20A to prevent the lines of magnetic force fromleaking from the housing 20A.

In the above embodiment, the two magnets 80, 82 are attached to therotating member 70, however the number of magnets is not limited to itand more magnets may be attached. For example, as shown in FIG. 6A, fourmagnets 80, 82, 84 and 86 may be attached to the surface of the rotatingmember 70 at intervals of 90 degrees. Preferably the four magnets arearranged so that their magnetic poles are alternately reversed.

Furthermore, as shown in FIG. 6B, the four magnets may be provided witha pair of rotating members 70A so as to be orthogonal. In this case, itis desirable to provide a spacer 76 made of a non-magnetic material forblocking the magnetic coupling between the two rotating members 70A,70A. Still another modification is shown in FIG. 6D, magnets 80, 82 withstacked an S pole and an N pole may be attached on both end portions ofthe rotating member 70A.

Next, a magnetic erasing device according to a second embodiment of thepresent invention will be described. FIG. 7A is a plane view of theinterior of the housing of the magnetic erasing device with the upperpart cut away, and FIG. 7B is a sectional view taken along the line B-B.The magnetic erasing device 10A according to the second embodimentincludes a support plate 200 that separates the internal space of thehousing 20 in the horizontal direction, unlike in the first embodiment.A motor 50 is accommodated in one space separated by the support plate200. A rotation mechanism including rod-shaped first and second magnets210, 220 is accommodated in the other space.

The motor 50 is operated by an electric power from a battery (not shown)and its drive shaft 52 is connected to a gear 230 through the supportplate 200. Two gears 232, 234 are meshed with the gear 230. The firstmagnet 210 has a cylindrical shape and has an S pole and an N poleextending along the axial direction as shown in FIG. 8A. One end of thefirst magnet 210 is rotatably attached to the support plate 200 by ashaft 212 and the other end is rotatably attached to the housing 20 by ashaft 214. Further, the gear 232 is attached to one end of the firstmagnet 210. The second magnet 220 also has the same configuration as thefirst magnet 210, one end of which is rotatably attached to the supportplate 200 by a shaft 222, the other end of which is connected by a shaft224 to the housing 20. The gear 234 is attached to one end of the secondmagnet 220. In such configurations, as the drive shaft of the motor 50rotates, its rotation is transmitted to the first and second magnets210, 220 via the gears 230, 232 and 234.

By driving the gears 232, 234 a5 both sides by the gear 230, it ispossible to form a desired distance (r1+r2) between the first and secondmagnets 210, 220. In this example, since the gear 232 and the gear 234have different diameters, r1 is not equal to r2, but r1=r2 is alsopossible. In case of r1=r2, the magnetic poles of the first and secondmagnets 210, 220 are preferably synchronized. Synchronization means thatthe angular position of the S pole of the first magnet 210 and theangular position of the S pole of the second magnet 220 are equal. Also,the first and second magnets 210, 220 are located at the depth ofdistance d from the open end 24 of the housing 20. Depending on thedistance d and the space between the first and second magnets 210, 220,the horizontal component of the lines of magnetic force at the housingend portion can be adjusted.

In the second embodiment as well, since the first and second magnets210, 220 are rotated, the direction of the lines of magnetic forcebetween the first and second magnets 210, 220 is constantly changed. Theerasable area by the magnetic erasing device of the second embodiment isa rectangular area defined by the space (r1+r2) between the first andsecond magnets 210, 220 and the axial length of the first and secondmagnets 210, 220. It should be noted that the magnet used in the secondembodiment may be a rectangular parallelepiped magnet as shown in FIG.8B.

In the second embodiment, the first and second magnets 210, 220 arerotated by the gears 232 and 234, but the second embodiment is notnecessarily limited to such configurations. For example, only the firstmagnet 210 may be rotated by the power from the motor 50 and the secondmagnet 220 may be rotated by the magnetic force from the first magnet210.

FIGS. 8C-8E show a modified example of the second embodiment. FIG. 8Cshows a single cylindrical (sor of rod) permanent magnet 250 rotated bya motor. Also in this configuration, the lines of magnetic force changewithin the internal space of the housing 20 to erase the magnetic panel.FIG. 8D shows a plurality of permanent magnets 260, 262, 264 in parallelrotated by using a rotating mechanism such as a gear. Each permanentmagnet 260, 262, 264 may be rotated synchronously or may be rotatedasynchronously. When the poles are synchronized, the change in themagnetic field may be uniform, but if the magnetic poles areasynchronous, the magnetic field may be random. FIG. 8E shows aplurality of permanent magnets 270, 272, 274 connected in series androtated. In this case, a constant space 280 may be formed between themagnets. As well, they may be rotated synchronously or asynchronously.

In case of rotating the rod-shaped magnet as shown in FIGS. 8C-8E by amotor, the shape of the housing may be a pen style as shown in FIG. 8F.The rod-shaped magnet 250 and so on are accommodated so as to extendalong the axial direction of the pen style housing 20B. Such pen typemagnetic erasing divide is suitable for erasing a fine region.

Next, a magnetic erasing device according to a third embodiment of thepresent invention will be described. The magnetic erasing device 10Baccording to the third embodiment generates and changes a magnetic fieldby an electromagnet. FIG. 9 shows a main part of the magnetic erasingdevice according to the third embodiment. The magnetic erasing device ofthe third embodiment includes an annular stator 300 made of a magneticmaterial such as iron in a housing. Eight protrusions 310 are integrallyformed on the inner periphery of the stator 300 at intervals of 45degrees. Coil 320 is wound around each of the eight protrusions 310.Here, for convenience, eight protrusions are referred to be a, b, c, d,/a, /b, /c, /d. The coils are wound around the protrusions a, b, c, d inthe same direction respectively, and the coils are wound around theprotrusions /a, /b, /c, /d in opposite directions with respect of theprotrusions a, b, c, d.

The magnetic erasing device further includes a driving circuit (notshown) for applying a current to the coils. The driving circuittemporally changes the magnetic field generated in the stator 300 byapplying a current, whose phase is shifted by 45 degrees, to the coilsas shown in FIG. 10A. First, in the time period T1-T2, the current pulseis applied to each coil of the protrusion “a” and the oppositeprotrusion “/a”. At this time, an N pole is generated at the tip of theprotrusion “a”, and an S pole is generated at the protrusion “/a”. Next,in the time period T 2-T 3, the current pulse is applied to each coil ofthe protrusion “b” and the opposite protrusion “/b”. At this time, an Npole is generated at the tip of the protrusion “b”, and an S pole isgenerated at the protrusion “/b”. Thereafter, similarly, in the timeperiod T3-T4, an N pole is generated in the protrusion “c”, an S pole isgenerated in the protrusion “/c”. In the time period T4-T5, an N pole isgenerated in the protrusion “d” and an S pole is generated in theprotrusion “/d”. In the next time period T 5-T 6, an N pole is generatedat the protrusion “/a”, and an S pole is generated at the protrusion“a”. Thereafter, N poles are generated sequentially at the protrusions“/b”, “/c” and “/d”, and S poles are generated at the protrusions “b”,“c”, and “d”. FIGS. 10A-10B shows an example in which N poles and Spoles make clockwise transition in the time periods T1 to T9. In thisway, the lines of magnetic force varied by 45 degrees are generated.

In the above example, the directions of the coils are inverted in orderto generate different magnetic poles on a pair of opposing protrusions.However, the present invention is not limited to it, and the coils woundaround all the protrusions may be oriented in the same direction, thena, b, c, d and /a, /b, /c, /d may be reversed.

In the above example, the current pulse is applied to the coil, however,the present invention is not limited to this wave. For example, thecurrent pulse may be a sinusoidal wave as shown in FIG. 12A, arectangular wave as shown in FIG. 12B, and a triangular wave as shown inFIG. 12C. If such positive and negative voltage waveform is applied, itis possible to generate N pole and S pole in the protrusions in onecycle of the waveform and the S pole and the N pole are generated at theopposite protrusions. In addition, the magnetic force can be adjusted byappropriately changing the magnitude of the current to flow and thenumber of turns of the coil.

The magnetic erasing device 10B shown in the third embodiment can erasecharacters or the like drawn on the magnetic panel 100 from the frontside or from the back side as well as the magnetic erasing device shownin the first and second embodiments.

Next, a modified example of the third embodiment is shown in FIG. 13 .The stator 302 shown in this figure has a rectangular shape. Fourprotrusions “a”, “b”, “/a”, “/b” are formed at an interval of 90 degreesat the inner periphery of the stator 302, and each coil is wound aroundeach protrusion. Also in this case, for example, when the current pulse,whose a phase is shifted by 90 degrees, is applied to the coils of theprotrusions “a”, “/a”, an N pole is generated at the protrusion “a” andan S pole is generated at the protrusion “/a”. When the current pulse isapplied to the coils of the protrusions “b” and “/b”, an N pole isgenerated at the protrusion “b” and an S pole is generated at theprotrusion “/b”. Thereafter, an N pole is generated at the protrusions“/a” and “/b”, an S pole is generated at the protrusions “a” and “b”.Note that the shape of the stator may be a polygon (for example, ahexagon) other than a rectangular shape.

Next, a fourth embodiment of the present invention will be described. Inthe fourth embodiment, as shown in FIG. 14A, a rod-shaped or cylindricaliron core 400, a coil 430 wound around the iron core 400, and currentapplying means 440 for applying a current to the coil 430 are prepared.The current applying means 440 applies the current, which has positiveand negative voltage cycles as shown in FIGS. 12A, 12B, and 12C, to thecoil 430 to invert the direction of the current flowing through the coil430. As the result, magnetic poles generated at both end portions of theiron core 400 change every half cycle. FIG. 14B schematically showsmagnetic poles generated at both end portions of the iron core 400 andthe lines of magnetic force M thereof. By appropriately selecting theaxial length of the iron core 400, lines of magnetic force M generatedfrom the both ends become substantially parallel to the axis. Therefore,the erasing efficiency could be enhanced and the color of the magneticpanel after the erasing could be clearer by the action of the horizontalcomponents of the lines of magnetic force to the magnetic panel.

FIG. 14C is a modified example of the iron core. The iron core 410 shownin this figure has leg portions 412 each extending in the verticaldirection from both end portions. With such legs 412, the lines ofmagnetic force are suppressed inside without beyond the legs 412. Thismakes it possible to clarify the boundary of the erasing area. FIG. 14Dis a further modified example of an iron core, in which leg portions 422are formed at both ends of the iron core 420 and in which extendingportions 424 each extending in the horizontal direction are furtherformed at the leg portions 422. Therefore, the lines of magnetic forcecan be further confined in the leg portions 422 and the extendingportions 424, and the erasing area becomes clearer.

The configuration of the electromagnet shown in the fourth embodimentcan be replaced by the rod-shaped permanent magnets 210 and 220 of themagnetic erasing device 10A shown in the second embodiments.

Although the preferred embodiments of the present invention have beendescribed in detail above, the present invention is not limited to thespecific embodiments, but various other modifications may be madewithout departing from the spirit and scope of the present invention asset forth in the appended claims. Modification/change is possible.

What is claimed is:
 1. A magnetic erasing device for a magnetophoretictype magnetic panel, the magnetophoretic type magnetic panel including aplurality of microcapsules arranged two-dimensionally, each microcapsuleincluding magnetic particles and nonmagnetic particles, the magneticerasing device comprising: a shaft rotatable about an axis; a magnetcomprising an S pole and an N pole, the magnet coupled to the shaft andextending along the axis; and a rotation mechanism coupled to the shaftso that the magnet is rotatable in a housing around the axis, wherein,during operation of the magnetic erasing device, lines of magnetic forcegenerated during rotation of the magnet are applied to the magneticparticles in the microcapsules to erase a visible image on the magneticpanel when the magnet is substantially parallel with and spaced from asurface of the magnetic panel by a predetermined distance.
 2. Themagnetic erasing device according to claim 1, wherein the magneticerasing device comprises a plurality of magnets connected in series, themagnet being one of the plurality of magnets.
 3. The magnetic erasingdevice according to claim 1, wherein the magnetic erasing devicecomprises a plurality of magnets and each magnet is connected inparallel, the magnet being one of the plurality of magnets.
 4. Themagnetic erasing device according to claim 1, wherein the magnet has acylindrical shape.
 5. The magnetic erasing device according to claim 1,wherein the magnet has a rectangular parallelepiped shape.
 6. Themagnetic erasing device according to claim 1, wherein the rotationmechanism comprises a motor comprising a drive shaft and a gear coupledbetween the shaft and the drive shaft.
 7. The magnetic erasing deviceaccording to claim 2, wherein the plurality of magnets are synchronouslyrotatable.
 8. The magnetic erasing device according to claim 2, whereinthe plurality of magnets are asynchronously rotatable.
 9. The magneticerasing device according to claim 3, wherein the plurality of magnetsare synchronously rotatable.
 10. The magnetic erasing device accordingto claim 3, wherein the plurality of magnets are asynchronouslyrotatable.
 11. A magnetic panel system comprising: a magnetophoretictype magnetic panel including a plurality of microcapsules arrangedtwo-dimensionally, each microcapsule including magnetic particles andnonmagnetic particles; and a magnetic erasing device for use in erasinga visible image on the magnetic panel, the magnetic erasing devicecomprising: a shaft rotatable about an axis; a magnet comprising an Spole and an N pole, the magnet coupled to the shaft and extending alongthe axis; and a rotation mechanism coupled to the shaft so that themagnet is rotatable in a housing around the axis, wherein, duringoperation, lines of magnetic force generated during rotation of themagnet are applied to the magnetic particles in the microcapsules toerase the visible image on the magnetic panel when the magnet issubstantially parallel with and spaced from a surface of the magneticpanel by a predetermined distance.
 12. The magnetic panel systemaccording to claim 11, wherein the magnetic erasing device comprises aplurality of magnets connected in series, the magnet being one of theplurality of magnets.
 13. The magnetic panel system according to claim11, wherein the magnetic erasing device comprises a plurality of magnetsand connected in parallel, the magnet being one of the plurality ofmagnets.
 14. The magnetic panel system according to claim 11, whereinthe magnet has a cylindrical shape.
 15. The magnetic panel systemaccording to claim 11, wherein the magnet has a rectangularparallelepiped shape.
 16. The magnetic panel system according to claim11, wherein the rotation mechanism comprises a motor comprising a driveshaft and a gear coupled between the shaft and the drive shaft.
 17. Themagnetic panel system according to claim 12, wherein the plurality ofmagnets are synchronously rotatable.
 18. The magnetic panel systemaccording to claim 12, wherein the plurality of magnets areasynchronously rotatable.
 19. A magnetic erasing device comprising: ahousing; a support plate separating the housing into first and secondinternal spaces; a motor disposed in the first internal space of thehousing; a plurality of magnets disposed in the second internal space ofthe housing, each magnet comprising an S pole and an N pole; a gearmechanism located between the motor and the magnets; a drive shaftcoupled between the motor and the gear mechanism, wherein, duringoperation of the magnetic erasing device, the motor causes the driveshaft to rotate so the magnetics rotate around an axis extending betweenthe support plate and an upper end of the housing.
 20. A systemcomprising: a magnetophoretic type magnetic panel comprising a pluralityof microcapsules arranged two-dimensionally, each microcapsule includingmagnetic particles and nonmagnetic particles; and the magnetic erasingdevice of claim 19 for erasing a visible image on the magnetic panelwhen the magnets are rotating and spaced from a surface of the magneticpanel by a predetermined distance.